Variant of integral, where you can specify a post-update
function, which receives the previous position as well as the current
(in that order). This is useful for limiting the output (think of
robot arms that can't be moved freely).

Depends: current instant if the post-update function is strict in
its first argument, previous instant if not.

Differentials

Derivative. Receives x and dt and calculates the change rate
dx/dt. Note that dt despite its name does not have to be time.

The exception handler function is called when dt is zero. That
function's result is the wire's output for those instants. If you
don't want to handle exceptional cases specially, just pass (^/) as
the handler function.

Objects are generalized integrals. They are controlled through
velocity and/or acceleration and can be collision-checked as well as
instantly teleported.

The post-move update function receives the world state and the
current object state. It is applied just before the wire produces
its output. You can use it to perform collision-checks or to limit
the velocity.